Vaxcyte’s VAX-31 High Dose Shows Superiority on 11 Serotypes, Enters Phase 3
Vaxcyte’s 31-valent VAX-31 elicited robust opsonophagocytic and IgG responses across 31 serotypes in 1,015 adults 50+, with the high dose non-inferior on 20 shared serotypes and superior on 11 unique serotypes. VAX-31 high-dose entered the OPUS Phase 3 program with topline data due Q4 2026.
1. Phase 1/2 Adult Trial Results
The randomized, observer-blind study enrolled 1,015 healthy adults aged 50+ to evaluate VAX-31 at low, middle and high doses versus Prevnar 20. The high dose met or exceeded opsonophagocytic activity non-inferiority for all 20 shared serotypes, achieved statistical superiority on 11 incremental serotypes, and showed a safety profile similar to PCV20.
2. Advancement to OPUS Phase 3 Program
Based on these results, VAX-31 high dose has entered the OPUS Phase 3 adult program with head-to-head non-inferiority trials against PCV20 and Capvaxive (PCV21). The program’s pivotal OPUS-1 trial will support a Biologics License Application with topline results due in Q4 2026.
3. Potential Coverage and Market Implications
VAX-31 is designed to cover approximately 95% of invasive pneumococcal disease and 88% of pneumonia in U.S. adults aged 50+, offering 14–34% broader IPD and 19–31% broader pneumonia coverage than standard vaccines. Success could position Vaxcyte’s carrier-sparing platform as a new industry benchmark for adult pneumococcal conjugate vaccines.